Output mean square sensing for magnetic output voltage regulator



J. V. MAJERCAK SQUARE SEN OUTPUT MEAN SING FOR MAGNETIC OUTPUT VOLTAGEREGULATOR Filed Sept. 20, 1955 Sept. 11, 1956 0252-3 mm oa QZ JOKPZOU OZQZ W530i 0Z4 JOmkZOO K Yuma-3124 95232 A mm m m @262? -SEzoo N H w :1 3\i m & mwzmoumzfit 059500 wz mzwm mmE n=2 OEMZQQE ATTORNEY United StatesPatent O M OUTPUT MEAN SQUARE SENSING FOR MAG- NETIC OUTPUT VOLTAGEREGULATOR John V. Majercak, Cleveland, Ohio, assignor to Jack &

Heintz, Inc., Cleveland, Ohio, a corporation of Delaware ApplicationSeptember 20, 1955, Serial No. 535,386

6 Claims. (Cl. 323-89) This invention relates in general to voltageregulators and has for one of its primary objects to provide an improvedvoltage regulator whose output will be proportional to the root meansquare value of the applied voltage, so as to make voltage regulationindependent of harmonic content of the applied voltage.

The conventional method of obtaining a signal proportional to the rootmean square value of the applied voltage in a voltage regulator is toapply the sensing voltage to the filament of a diode in a direct currentbridge circuit in such a manner that a change in the sensing voltageproduces an unbalance in the bridge and provides a direct current signalvoltage which is applied to the tubes and the tubes, in turn, controlthe output of a two stage gating magnetic amplifier.

In keeping with the stated primary object of my invention, I propose toprovide a voltage regulator consisting of a voltage sensing filamenttype diode whose output is fed directly into the control coils of amagnetic amplifier that is so constructed as to be a full Wave outputwith windings so arranged that all of the windings are used as controlwindings during the control half of the cycle and the power windings areused as such during the other half of the cycle. This arrangement makesit possible to use the voltage of the main power transformer as part ofthe reset voltage using both windings as control windings during thereset half of the cycle reducing control current requirements.

I further propose to employ a duodiode tube and a center tapped filamenttransformer so constructed and arranged that if one tube filament failsone diode of the tube will be shorted in order to make that half of thecircuit inoperative, while the other half of the circuit continues tooperate and regulate the voltage.

With the foregoing and other objects in view, the invention resides inthe combination of parts and in the details of construction hereinafterset forth in the following specification and appended claims, certainembodiments of which are illustrated in the accompanying drawing, whichis a circuit diagram of my improved root mean square sensing magneticamplifier voltage regulator.

Referring more particularly to the drawing, I have provided a sensingtransformer 1, with a primary winding 2 to be connected into the circuitwith the alternating current voltage to be controlled and acenter-tapped secondary winding 3 for supplying a twin filament 4 of aduodiode, generally indicated at 5. The center tap of the secondary oftransformer 1 is connected to the filament 4, at a common point betweenfilament sections 4a, 411 connected across different sections 3a, 3brespectively of the secondary 3 of transformer 1. The filament sectionsia, 4b cooperate in the manner of a diode with plates 6, 7 respectively.

The remainder of the circuit includes a power and plate transformer 8with a primary Winding 9. It also includes diode plate 6 of diode inseries with a secondary winding 10 of the power and plate transformer 82,762,968 Patented Sept. 11, 1956 and the secondary, or control, winding11 of a magnetic amplifier 12, the primary, or control and power winding13, of which is in series with a section 14a of a centertapped secondarywinding 14 of transformer 8. Likewise, diode plate 7 and filamentsection 4b of diode 5 are in series with a secondary winding 15 oftransformer 8 and with a control, or secondary, winding 16, of amagnetic amplifier 17, the primary, or control and power winding 18, ofwhich is in series with a section 14b of secondary winding 14 oftransformer 8.

The output terminals of the regulator are designated by the referencecharacter 19a, 19b. The terminal 19a is connected to the mid-point ofsecondary coil 14 and the terminal 1% is connected to the connectionbetween the winding 13 and the winding 11 of magnetic amplifier 12through a self-saturating rectifier 20 and to the connection between thewindings 16 and 18 of magnetic amplifier 17 through a self-saturatingrectifier 21. The rectifier 20 permits current to flow from the centertap on the secondary coil 14 through the winding 13 when the center tapis positive with respect to the other end of section 14a of thesecondary coil 14 and the rectifier 21 permits current to flow from thecenter tap through the winding 18 of magnetic amplifier 17 when thecenter tap of secondary coil 14 is positive with respect to the otherend of section 141) of coil 14. It can thus be seen that when outputcurrent is flowing through winding 13 of amplifier 12, the polarity ofsecondary section 13b will be such that no output current flows throughwinding 18 of amplifier 17 and vice versa. The output terminals 19a, 1%are connected to the load and current controlled in accordance with theinput voltage to sensing transformer 1 is supplied to the load which maybe the field winding of an alternator.

The amplifiers 12, 17 may be termed gating magnetic amplifiers which areconnected in push-pull relationship. Each gating magnetic amplifier hasa control or reset cycle under the control of diode 5 followed by afiring or conduction cycle where output current from secondary coil 13flows in the power winding. At any given half cycle of applied voltageone gating magnetic amplifier will be resetting while the other will beconducting.

On the half cycle, when the polarities of the power and platetransformer 8 are such that the center tap of secondary coil 14 ispositive with respect to the other end of section 14b, output currentwill flow in a circuit containing winding 19 of transformer 8, thecontrol and power winding 18 of gating magnetic amplifier 17, rectifier21, and the output. The control and power winding 18 of the gatingmagnetic amplifier 17 will have a high impedance at the beginning partof the half cycles where output current is flowing and then willsaturate due to the magnetizing effect of the output current and allowmaximum current to flow for the remainder of that same half cyclethrough the load.

The level of magnetization at the beginning of the half cycle determinesthe amount of current flowing through the load during the half cycle bydetermining the time in the cycle necessary to saturate the core of themagnetic amplifier. During the same half cycle that output current isflowing in magnetic amplifier 17, the core of the gating magneticamplifier 12 is being reset to a predetermined level of magnetization asdetermined by transformer 1 since the polarity of secondary coil 10 issuch that the plate 6 is positive with respect to filament 4 and resetcurrent will flow through the following circuit: from secondary coil 15through plate 7 of diode 5, through filament section 4a to the centertap of power and plate transformer 8, through winding 14a of the sametransformer, through control and power winding 13, control winding 11,and back to power and plate transformer winding 10. The

filament section 4a of diode 5. A rheostat 23 may be connected in serieswith the primary 2 of transformer 1 to adjust the output voltage to suitthe particular conditions. On the next half cycle the reset andconduction cycles interchange between the gating magnetic ampiificrs dueto the change in polarities of the secondary coils it '14- and 15. Itwill be noted that current cannot flow in the control windings of 11,160i the amplifiers 12, 17 on the respective half cycles when outputcurrent is flowing in the control and power windings 13, 18 respectivelysince the polarities of secondary coils l0, 15 respectively are suchthat the plate of diode connected in the respective reset circuit isnegative with respect to the corresponding filament section. Therectifiers 20, 21 prevent current from the secondary coil 14 fromflowing in windings 13, 11? respectively when the amplifiers 12, 17respectively are being reset. Thus, every half cycle one magneticamplifier is conducting through the load while the other is reseting.

A rectifier 24 connected across the output is used as an inductanceisolating rectifier when the output of the regulator supplies power toinductive load such as an alternator control field winding. Thisrectifier permits current flow through the output and through rectifier24 due to stored energy of the inductive load.

The inner ends of each of the filament sections 4a, 4b are connected toa fixed support 24 in the tube of the duo-diode by resilient arms 25, 26respectively, which are fixed at one of their ends to the support 24 andat their outer ends to the inner end of their respective filamentsections. The bias of the arms 25, 26 is such that if the filamentsections 4a, 4b break, the arms connected thereto will move intoengagement with members 27, 2.8 respectively, connected to the plates 6,7 respectively, to form a short circuit from the support 24 to theplates. if only one filament section breaks, only the arm connectedthereto Will'CflUSB a short circuit between the support 24 and thecorresponding member 27 or 28.

The connection between the center tap of secondary coil l4and thefilament 4 is made at the point 24 and when either of the arms 25, 26contacts its corresponding member 27 or 23 a shortcircuit is completedwhich will allow sufficient control current to flow in the reset or corntrol cycle that on the half cycle, which is normally the reset orcontrol cycle the level of magnetization is reduced to a pointwher'esubstantially no current will flow on the output cycle. The otherhalf of the duodiode and the other amplifier will continue functioningin the normal manner unless the corresponding filament section alsobreaks.

As stated before, the primary object is to provide a voltage regulatorwhose output is proportional to the root mean square value of theapplied voltage, thus making voltage regulation independent of harmoniccontent of the applied voltage. By means of my improved voltageregulator, the output of the voltage sensing filament type diode 5 isfed directly into the control coils 19 and in of the magnetic amplifiers11 and 17. The magnetic amplifier is a full wave'output with windings soarranged that all of the windings 10, 12, 16 and 18 are used as controlwindings during their respective control half of the cycle and thepowerwindings 12 andlS are used as such during their'respective outputhalf of the cycle. Using both sets of windings'as control windingsduring the reset half of the cycle reduces control current requirements.

'In view of thefact that the sensing tube 5 has its filament l'centertapped at 23, if one section of the filament fails, one diode of thetube will be shorted, due to the internalconstruction of thetube, so asto make that half d of the circuit inoperative, while the other sectionwill continue to operate and regulate.

While I have referred to rectifiers 20 and 21 as being self-saturatingit is to be understood that I may also employ rectifiers that are notself-saturating.

What I claim is:

1. In a root mean square sensing magnetic amplifier output voltageregulator, a twin voltage sensing filament type diode, a sensingtransformer for supplying the filament of said twin diode, a power andplate transformer, a plurality of magnetic amplifiers each having acontrol winding and a control and power winding, each of said diodesbeing in series with said power and plate transformer and with thecontrol winding of its respective magnetic amplifier, said twin diodebeing provided with a center tapped filament havng respective sectionsin series with the control windings of said magnetic amplifiers.

2. in a root mean square sensing magnetic amplifier output voltageregulator, a voltage sensing filament type twin diode, a sensingtransformer for supplying the filament of said twin diode, a power andplate transformer, 21 first and second magnetic amplifier each having acontrol winding and a control and power winding, each one of said diodesbeing in series with a different secondary winding of said power andplate transformer and with the control winding of a 'difierent one ofsaid magnetic amplifiers.

3.. In a voltage regulator, first and second magnetic amplifiersconnected in push-pull relationship, each of said amplifiers havingoutput windings and control winding, first and second control circuitsfor controlling the current in the control winding of said first andsecond magnetic amplifiers respectively, each of said circuitsincluding-a diode having a filament and a plate, means controlling -theemission of said filaments in accordance with a voltage condition tothereby determine the current conducted by the diodes, each of saiddiodes including means for establishing a circuit therethrough uponfailure of its filament to maintain a complete control circuit for therespective control winding.

4. In a voltage regulator, first and second magnetic amplifiersconnected in pushepull relationship, each of said amplifiers havingoutput windings and control winding, first and second control circuitsfor controlling the current in the control winding of said first andsecond magnetic amplifiers respectively, each of said circuits includinga diode having a filament and a plate, a transformer having a centertapped secondary with the first and second sections thereof connected inseries with the filamentsof said first and second diodes respectivelyfor controlling the emission of said filaments in accordance with-avoltage condition to thereby determine the current conducted by thediodes, each of said diodes including means forestablishing a circuittherethrough upon failure of its filament to maintain a complete controlcircuit for the respective control winding, each of said controlcircuits reducing the output of its corresponding magnetic amplifiersubstantially to zero upon the breaking of the filament in itscorresponding diode.

5. In a voltage regulator, first and second magnetic amplifiersconnected in push-pull relationship, each of said-amplifiers havingoutput windings and control winding, first and second control circuitsfor controlling the current in the control winding of said first andsecond magnetic amplifiers respectively, each of said circuits includinga diode having a filament and a plate, a transformer having a centertapped secondary with the first and second sections thereof connected inseries with the filaments of said first and second diodes respectivelyfor controlling the emission of said filaments in accordance with avoltage condition to thereby determine the 50.11- rent conducted bythediodes, each of said diodes includmg means for establishing a circuittherethrough upon failure of .its filament to maintain a completecontrol circuit 'for the respective control winding, each of saidcontrol circuits reducing the output of its corresponding magneticamplifier substantially to zero upon the breaking of the filament in itscorresponding diode, said diodes being provided by a single duodiodehaving twin filaments and plates and the primary of said transformerbeing 5 connected into a circuit having a voltage condition to becontrolled and the output of said amplifiers being utilized to controlsaid volt-age condition.

6. In a voltage regulator, a voltage twin filament type diode, havingfirst and second plates and first and second 10 filaments providing twodiodes, a sensing transformer for supplying power to said filaments, apower and plate transformer having a plurality of secondary windings,first and second magnetic amplifiers each having a control winding andan output winding, said diodes being 15 References Cited in the file ofthis patent UNITED STATES PATENTS 2,714,188 Scherer July 26, 19552,734,165 Lufcy et a1 Feb. 7, 1956 FOREIGN PATENTS 723,253 Great BritainFeb. 2, 1955

